1. Field of the Invention
The present invention relates to a glass for a window of a semiconductor package, a glass window for a semiconductor package, a process for the production of the glass window and a semiconductor package. More specifically, the present invention, relates to a glass for use as a window of a semiconductor package made of a plastic for encasing a solid image sensing device of a digital camera or a VTR camera, glass window for the above semiconductor package such as a glass window for a semiconductor package having the function of a near infrared absorption filter for correcting the color sensitivity of sensing device of CCD, a process for the production of the glass window, and a semiconductor package having the above glass window, a semiconductor device and a package for encasing the semiconductor device.
2. Prior Art
A semiconductor device such as CCD causes a soft error due to a ray emitted from a window glass for a package, so that it is required to decrease the amount of radioactive isotope contained in the window glass which radioactive isotope emits a ray. As a glass for semiconductor package window material whose α-ray emission is controlled, for example, JP-A-8-306894 discloses a window glass for a semiconductor package which window glass has its U and Th contents controlled to be 5 ppb or less.
With the downsizing of digital cameras and spreading of cellular phones with a camera in recent years, a high-pixel and small-sized image sensing system is being demanded. The size and thickness of all of components such as a lens, a filter, a package, etc., are decreasing. Further, besides a decrease in the size and thickness, it is proposed to form of a composite unit of components. For example, the above JP-A-8-306894 discloses not only a transparent window glass for a semiconductor package but also a window glass for a semiconductor package which window glass contains CuO and absorbs near infrared wavelength.
A conventional glass for the window of a semiconductor package has a relatively small thermal expansion coefficient, since it is adjusted to have a thermal expansion property corresponding to the thermal expansion property of a package made of ceramic such as an alumina, or the like. When bonded to a package made of a plastic, therefore, the above glass causes the package to be distorted or deformed or is broken due to a thermal expansion difference, so that such a glass is a bar against the use of a plastic material for decreasing the weight of a package.